PSEUDOMOMENT STELLAR DYNAMICS .1. SPHEROIDAL GALACTIC EQUILIBRIA

A system of pseudomoment fluid equations is developed and applied to t he study of spherically distributed stellar populations. The first equ ation in the pseudomoment hierarchy is formally analogous to the Jeans equations except for the simplifying absence of a term proportional t o a (radially) differentiated pseudomoment dispersion (or inverse ''te mperature''). From the next set of equations in the pseduomoment hiera rchy a simple relation between stellar nonisothermality and radial ani sotropy variation is obtained and shown to yield an increasing radial anisotropy with Galactocentric distance for realistic models. A simple relation is derived between the stellar radial pseudomoment dispersio n and the circular speed profile. Using the rotation curve analysis of Salucci and Frenk (1992), an increasing rate of falloff in the stella r number density with radius is predicted, for which some observationa l support exists (Saha 1985). An additional relation between the densi ty and potential for a mildly flattened tracer population is derived a nd applied toward an estimate for the asphericity of the Galactic pote ntial and the dark halo. Based on Hawkins's (1984) study of RR Lyrae s tars within 60 kpc, a nearly spherical Galactic potential and a mildly flattened dark halo (q(rho) approximate to 0.7) are indicated.